The present invention relates to an antenna arrangement according to and a radio set.
The publication, xe2x80x9cIEEE Transactions on Antennas and Propagation,xe2x80x9d Vol. 45, No. 10, October 1997, describes a dual-frequency planar inverted-F antenna, which contains a radiating element, a plurality of reference potential connections, and a supply connection. The radiating element is resonant in a first operating frequency range at roughly 1.8 GHz and in a second operating frequency range, different from the first operating frequency range, at roughly 0.9 GHz. In this context, the radiating element is supplied with signals via the supply connection either in the first operating frequency range or in the second operating frequency range.
In contrast, the antenna arrangement according to the present invention has the advantage that the reference potential connection is connected to the reference potential of a reference potential surface via a first impendance that, has a high resistance in the first operating frequency range and low resistance in the second operating frequency range. By terminating the reference potential connection in a frequency-selective manner, the radiating element, and the antenna arrangement, is resonant in both the first operating frequency range and the second operating frequency range, and radiates effectively. In the radiating element, no precautions are necessary such as an L-shaped incision for creating two partial radiating elements, thus the effort involved in manufacturing the antenna arrangement and the costs related thereto can be kept low.
It is particularly advantageous that the first impedance is configured as a line whose length is selected such that the line impedance has low resistance in the second operating frequency range and high resistance in the first operating frequency range. The second operating frequency range has frequencies that are roughly half as large as the frequencies of the first operating frequency range. This represents a particularly simple realization of the frequency-selective termination of the reference potential connection of the antenna arrangement.
It is advantageous if the length of the line corresponds to roughly one fourth of the operating wavelength of the second operating frequency range, and if the line runs in open circuit. In this manner, for the second operating frequency range, the line constitutes a short-circuit and, for the first operating frequency range, it constitutes an open circuit between the reference potential connection and the reference potential. Thus the necessary low-resistance or high-resistance first impedance can be produced simply and in a space-saving manner.
The same advantage is gained by using, for the first impedance, a resonant circuit whose resonance frequency lies roughly within the second operating frequency range. The resonant circuit therefore represents a particularly low-resistance impedance in the second operating frequency range and has a high resistance for frequencies of the first operating frequency range.
A further advantage is that the first impedance is configured as a semiconductor component, for example a PIN diode. In this way, the first impedance does not depend on the frequencies of the two selected operating frequency ranges, and the antenna can be switched electronically between its operating frequencies.
A further advantage is that the length of the radiating element, the height of the supply connection and of the reference potential connection of the antenna arrangement, and the distance between the supply connection and the reference potential connection are determined such that the input resistance of the antenna arrangement at the supply connection is roughly the same for both operating frequency ranges. In this manner, the input resistance of the antenna arrangement, in a simple manner on the basis of the corresponding geometric dimensioning of the antenna arrangement, for both operating frequency ranges without impedance transformation, can be linked to an antenna network for the supply and reception of radio signals, so that savings are achieved with respect to components, space, and cost.
A further advantage is that a second impedance is provided that transforms an output resistance of an antenna network such that it is adjusted in both operating frequency ranges to the respective input resistance of the antenna arrangement at the supply connection. In this manner, an impedance adjustment between the output resistance of the antenna network and the input resistance of the antenna arrangement at the supply connection can be realized irrespective of the geometry of the antenna arrangement, so that the geometric dimensions of the antenna arrangement are not subject to fixed requirements and the antenna arrangement can be adjusted to spatial circumstances or limitations.
A further advantage is that the second impedance is configured as a line whose length corresponds to one fourth of the operating wavelength of the second operating frequency range. The second operating frequency range having frequencies that are roughly half as large as the frequencies of the first operating frequency range. In this manner, the second impedance can be realized in a particularly simple and cost-effective manner.
A further advantage is that the radiating element is bent. In this manner, the antenna arrangement can be reduced in size and space can be saved without reducing the effectiveness of the antenna.
A further advantage is that the antenna arrangement is embedded in a material whose dielectric constant is significantly larger than 1. In this manner, both a reduction in size of the antenna, and thus space savings, can be achieved without significantly reducing the effectiveness of the antenna.
It is advantageous to use an antenna arrangement according to the present invention in a radio set. A radio set of this type can be operated in a simple, inexpensive, cost- and space-saving manner in two different operating frequency ranges without reducing the effectiveness of the antenna in the two operating frequency ranges.